The circuit of the present invention relates generally to motor control circuits and more particularly to brushless motor position monitoring circuits incorporated therein. It is known to attach hall effect sensors to motor windings for sending digital signals indicating motor position to an IC commutation logic circuit. The commutation logic generates a select pulse sequence at the output phase winding drive signals so as to cause the motor to rotate in a desired manner. Prior art circuits utilized external components outside of the IC, typically resistor, capacitor and/or inductor types of low pass filters, to suppress noise spikes. Such low pass filters were generally custom fit according to the particular motor application. Accordingly, for each different application a different set of RC components was required for proper effective filter operation.
Prior to the present invention, previous commutation logic circuits did not utilize digital filtering. As mentioned above, external components were utilized for noise filtration. There were no provisions for recording or observing distance traveled by the motor (total number of motor rotations) and the control circuits were very sensitive to signal transients on the hall effect sensor inputs.
What is needed is a motor position monitoring apparatus for use in motor control circuits for monitoring the position of a motor and for providing information relating to the total distance traveled by the motor.
A motor position monitoring apparatus is also needed that is noise tolerant and that can filter very noisy inputs from hall effect position sensors. Given proper filtering, the position monitoring apparatus can operate in noisy environments such as in industrial control applications and automotive applications such as when placed in the vicinity of spark plug wires or other vehicle electronics.